Manufacture of spinnerettes



xpr 29, wm. M. SCHNEIDER 292399979 MANUFACTURE oF SPINNERTTES Filed Jan.11, 1938 FACTURE' 0F SPHNNHIRIETTES ration of Delaware ApplicationJanuary ll, 1938, Serial No. 184,425

3 Claims.

This-invention is directed to the preparation of perforated plates and aspecific example being the preparation of spinnerettes for use in theproduction of cellulosic filaments of artificial origin. It isparticularly concerned with the procedure whereby the polishing of theplate or spinnerette may be expedited.

In the spinning of artificial silk, the cellulosic solution is extrudedthrough .a spinnerette, containing many extremely fine holes into aspinning bath, the filaments thus precipitated being combined to formthe artificial silk threads.

It is common practice to use precious metals or alloys of preciousmetals as the material of which the spinnerette is made. An alloy ofplatinum land gold (70% gold and 30% platinum) is one that is commonlyused in the manufacture of spinnerettes for use in the production ofartificial silk by the viscose process.

In the production of such spinnerettes, it is the practice to punch outthe draw plate in vsuch a manner as to Iprovide many imperforateprojections, corresponding tothe number of spinning holes desired. Theouter ends of the nibs or tips or imperforate projections are thengroundioi with a mild abrasive, in order to provide openings in the drawplate. A needle is then forced into each opening in order to give theman accurate circular shape and a uniform diameter.

Such a procedure leaves a slight burr at the outer surface of eachopening, and in view of the nature of the alloy and the extremely smallsize of the openings considerable difliculty is encountered in removingthis burr without altering the shape of the opening. It is the practiceto remove this burr by polishing the outer surface of the draw plate.

It is an object of the present invention to provide an improvedprocedure whereby the burr may be removed from these and similaropenings without injury to the shape or size of the openings. A furtherobject is to provide a procedure by which spinnerette openings of thedesired shape and size may be prepared. Other objects will becomeapparent.

In describing the invention, reference will be nerette lll is given the`general configuration shown in Figure l with the integral draw plate l land the integral outwardly extending flange l2. By the subsequent stepshereinbefore referred to, the openings are formed as illustrated inFigure 2, the openings being illustrated at I3 and the burr at the lowerend of each opening being illustrated at lli.

A film-forming coating composition l5 is then applied to the lowersurface of the draw plate between the openings, but leaving the portionof the metal around each opening exposed. This coating composition isapplied to prevent the electrolytic deposition of metal to thespinnerette, in the steps hereinafter described, except around eachhole. It should be capable of forming a continuous'nonporous lm that isadherent to the metal of the draw plate and that is not affected by theelectrolyte or the electrolytic action.

A film of parain may be used for this purpose Aor some other coatingcomposition that will adhere to the metal. A suitable composition is onecontaining a low viscosity nitrocellulose (1/ sec. R. F. gun cotton)together with the solvents for the nitrocellulose and solvent softenersor plasticizers that are commonly used in the preparation ofnitrocellulose paints and lacquers. For example. solvents such as ethylacetate, butanol, toluol, or acetone oil, etc., and solvent softeners orplasticizers such as dibutyl phthalate, tricresyl phosphates, castoroil, etc., and resins such as shellac, etc., may be incorporated to givethe desired characteristics to the coating composition. In someinstances it may be desirable to use a coating composition that willadhere to the metal during the subsequent heating. If such a coatingcomposition is used it may, if desired, be colored to give it a colordistinctly different from that of the metal of the draw plate so that itwill serve as a guide in the subsequent polishing operation. Dyes orpigments'may be added to a suitable lacquer or coating composition inorder to give the desired color.

When the coating composition has been applied to cover all portions ofthe spinnerette which are to be immersed. except around the openings,

the spinnerette (which preferably has been previously subjected to acleaning solution to obtain a'surface free from contamination) is placedin a suitable electroplating bath and the openings in the drawplate areplated with a metal, such as nickel, chromium or copper. Nickel is thepreferred metal for this purpose but copper and chromium may also beused. Copper may have the drawback of being not quite hard enough withsome alloys.

By this operation, a plug or rim of metal i6 is deposited at each hole.-Due to the small size of the openings, the plating will not extend veryfar within the hole. It is preferably discontinued before the hole isentirely closed, as illustrated in Figure .4. Y

Each hole is then lled with a plug il of resinous or other suitablematerial. 'Ihis material should be suilciently hard to reinforce thehole and prevent it from being deformed during thelpolishing action. Itshould have a melting point and/or hardening point below the temperatureat which the alloy of the spinnerette would lose its temper. For aplatinum-gold alloy' as described above, it should have a melting pointbelow 500 C.

A phenol-formaldehyde resin which will harden on baking at temperaturesbelow the temper point of the metal or allow of the spinnerette, forexample, below 4500 C. and preferably at about 150 to 200 C., may beused for this purpose. In using such a resin it may be poured or forcedinto the holes in a liquid or plastic state so as to completely ll theopening in the draw plate and in the rim i6. It is then baked (forexample, at about 150 to 200 C., for about 3 hours with the abovedescribed resin) to harden it suiiiciently to give the desiredreinforcing. If a phenol formaldehyde resin is used for this purpose, itmay be one which is liquid in the A state of polymerization and whichwill be converted to the B state on heating to the temperaturesdescribed.

Other resins or other materials may be used in place of the Bakeliteresin. Such materials should be such as to not contract on hardeningand' as to not expand upon hardening so as to apply pressures that woulddeform the openings. Materials which will harden on cooling and withoutbaking maybe used in place of bake plug. Plug materials which are toobrittle, such as Woods metal (antimony-zinc alloy) and plug materialswhich are too softand which `smear, as wax, are not suitable for use inthis procedure but various substances intermediate between these may beused.

After the plug has hardened, the draw plate is subjected to a polishingoperation whereby it is polished down to its natural surface. In thisoperation any of the film-forming substance l5 remaining is completelyremoved and, if colored,

tirely removed, the spinnerette may be placed in an acid, such as hotconcentrated nitric acid, or other suitable solvent for the platedmetal, but which will not attack the metal or alloy of the spinnerette.Obviously other solvents for the plug or for the plated metal may beused, if desired.

f Tlie plating l 6 at the rim of each hole prevents the irregularbreaking oli' of the burr at the edge of the hole during the polishingoperation. The plug of resinous material reinforces the inside of theopening and assists in preventing a breaking olf of the burr. It alsoprevents the portions of the burr or of the plating material, which areremoved during the plating, from being forced into the openings and'plugging them.

'Ihe nished draw plate, as illustrated in Figure 7, has perfect openingswhich are of the same shape and diameter as. the holes formed bytheneedle.

It is apparent that the invention -may'have many and varied applicationsand it islnot intended to restrict it to the particular use orembodiment described above. In makingf other uses of it, certainvariations may be required or desirable in the materials used or in theparticular sequence of steps or to the other details of operationdescribed. The terms u'sed have been used as terms of description andnot terms of limitation and it is intended that all equivalents thereofbe included within the scope of the appended claims.

What is claimed:

1. In the preparation of spinnerettes, the steps comprising providing aplurality of holes of the desired size and shape in the Idraw plate,applying -a, nitrocellulose coating composition of a color diierent fromthat of the metal of the spinnerette to prevent the electrodeposition ofmetal except serve as a guide to indicate'when the polishing iscompleted. In the novel process it is not essential that the film act asa visual indicator of the completion of the polishing operation inasmuchas the deposited metal surrounding the bpenings will serve the samepurpose. It may serve this purpose by either being a different color orif the same color by reason of the plated portion extending above thesurface of the plate.

Figure 6 shows the plate after the polishing operation. The spinneretteis then placed in a solvent. for the resin or other plug material,L

whereby the remaining portion of the plug |1` is removed. If a Bakeliteresin asdescribed above is used, hot concentrated sulphuric acid may beused as the solvent.'

, If the openings in the draw plate are small enough (asin-the-spinnerettes used in preparing viscose artiicial'silk), theplatingl will not extend within the openingV .beyond the line of theface of the draw'plate. In that event, it will bel entirely removed withthe burr. If it is not enon and around any-metal projecting beyond thesurface of the draw plate. electrodepositing a metal upon the inner andouter surfaces of any metal projections, filling said holes with aphenol formaldehyde resin that is liquid at about normal roomtemperatures and which solidies on baking at about to200", C., baking tosolidify the resin, polishing the surface of the draw plate' to removeany metal projections and the metal plated thereon and the coatingcomposition, and dissolving the resin from the holes.

2. In .the preparation of spinnerettes, the steps comprising providing aplurality of holes of the .desired size and shape in the draw plate;applying a iilmforming`organic insulating coating composition of a colordifferent from that of the metal of the spinnerette to prevent theelectro-deposition of metal except on and around any metal projectingbeyond the surface of the draw plate; electro-depositing a metal uponthe inner and outer surfaces of any metal projections; lling said holeswith a resinous material, said material being liquid at normal roomtemperatures and having a melting point below the temperature at whichthe metal of the spinnerette would lose its temper; baking to solidifythe resinous material, polishing the surface. of the draw plate toremove any metal projections as well as the metal plated thereon and thecoating of a platinum-gold alloy, the steps comprising.

' providing a plurality of holes' ofthe desired size and shape in thedraw plate; applying animforming organic insulating coating composition4of a color diierent from that of the alloy oi the spinnerette to preventthe electro-deposition of metal except on and around any alloyprojecting beyond the surface of` the drawvplete; electrodepositing ametal upon the inner and outer surfaces of any alloy projections:filling seid holes with a, resinous material, said material b liquid atnormal room temperatures end having a melting point below 500 C.; bakingto solidify the resinous materiel; polishing the surface of the drewplete to )remove any alloy projections as well es the metal platedthereon and the coating composition; and dissolving and removing theresinous materiel from the holes.

Administramr of the Estate of Maa: Schneider,

Deceased.

